Process of electrolytically refining copper or copper alloys



May 6,1930; M. HQSENFELDHAL 1,757,047.I

PROCESS 0F ELECTROLYTICALLY REFI'NING COPPER 0R COPPER ALLOYS Filed July 24. 1926 I lll Orne/.75,

Patented May 6,

QNIIED STATES MABTINYHosENrELD, or BERLIN-SIEMENSSTADT, AND `GNTHER HNsEL, or BERLIN- CIIAELOTTENBUEG, GERMANY, AssIGNoEs. To sIEMENs a HALsxE, AKTIENGE- ENss'rADr, NEAR BERLIN, GERMANY, A GERMAN coEroEA- PROCESS F ELECTROLYTICALLY BEFINING'CZPPER QR COPPER ALLOYS Application ined my 24, 192s, semi No.

Our invention relates to a new process of electrolytically rening copper or copper 'alloys and to an improved apparatusfor this process. l a

g In the electrolytic refining of impure copperpart of the impurities goes into the sludge and part dissolves in the electrolyte and grad-I ually becomes more and more concentrated therein. For each quantity of impurities that dissolves in the electrolytethe electrolyte becomes poorer in the working to the extent of the chemically equivalent quantity of copper. This phenomenon occurs to a relatively a and inconvenient. The

i dered porerin copper to such an extent that copper sulphate is obtainedcas the copper separates at the cathode only in a powdered or spongy condition. In orderA to keep the copper concentration in the electrolyte constant to some extent it has been necessary to add cop er sulphate continually to the electrolyte. uch a mode of operation is economical only in processes in whichthe by-product. These conditionsA also obtain in the case of A copper alloys which contain rather large quantities of other 'soluble metals, such as nickel, cobalt, etc. If copper bronzes, i. e.,

'tin-are treated whilst employing the usual copper-containing electrolytes, the tin inthe form of stannic acid goes into the anode Y sludge, so that the above mentionedimpoverishment as to copper itself does not take place. The stannic acid separating out gives rise, however, to other disturbin factors. It 4is known that the larger part o such stannic acid separates outvery readily inv 'colloidal kform. -There have been employed for precipitating the stannic acid -variousprocesses 124,754, and in Germany January 6, 1926.

which are based on heating and then suddenly cooling the liquor outside thebaths, or on the addition of certain substances to theliq-` uor etc., all being processes' which complicatel the operation. l Attempts have for a long time been made to increase the copper content of the liquor or to keep it constant in some other way. As such an attempt may be mentioned the use of electrolytes containing cu rous chloride. It should however, be notedt at in the case of the known experiments itis a questionof doubling the yieldper ampere-hour, and thus reducing the size of the monovalent copper. v

Now the object of the present invention is Y likewise to use' a cuprous chloride solution as electrol te, but to keep its copper content constant y special means. If a cuprous chloride solution be used Aas electrolyte, the' liquor flowing from thebaths can, according to the invention, be oxidizedto cupric chloride by the addition'of oxidizing means and this cupric chloride can be reduced to cuprous chloride by taking up suitable'A quantities of 'copper whereby the vcopper content vis restored to the priginal;percentage. d v

This` process is especially suitable for reiningalloys of copper which contain rather 1 large quantities ofnickel, cobalt, tin etc., or

plant, by using a '65 adrnixtures which are likewise soluble in the cuprous chloride electrolyte f Asoxidizing means for theoxidation of the cuprous chloride to cupric chloride there is preferably employed a gaseous agent suchl as,-or example, air or chlorine.

For the re- A duction `of ,the resulting cupric chloride soluy v tion it i's most advantageous to use, instead alloys containlng rather large. amounts of.

of pure metallic copper, black copper which it is intended to refine or the copper alloy itself vwhich it isfintended to refine. D

:It is evident -that the electrolyte will, in the course of working, becomerlcher in the soluble admixtures tothe copper,such as zinc in the form of zinc chloride, nickel in the for-m of nickel chloride, etc., and consequent- 1y. from time to time a purification ofthe electrolyteby` removing these compounds must be undertaken. This purification ,may be effected -by one of the'comm'only known chemical processes.

chemical 'process can also be employed for this purpose In liter; it is. likewise advantageous to a the last remnant of copper from the electrolyte the remaining components--for example nickel, tin, cally tentials. The chlorine produced at the anode .at the same time can be again used as oxidizing means as above described.` It has lbeen found to be advantageous for carrying out the aforesaid process to add from timeto time to the electrolyte during the oxidation stage a smalll quantity of hydrochloric acid-#for example 10 to 20 grains colloid-for example 1 gram of gelatine per liter of electrolyte-fte the electrolyte for the sumed that an alloyv of "zinc, containing about 70% '257 cording to the purpose of obtaining a goodJ cathodic deposit of copper.

copper,-nickel, and

to be rened acl nickel, and 10% of zinc, is

As electrolyzer new process.-

' there is employed oneof the known usual arrangements 1n cathode, a plate of electrolytic copper can be 'em loyedf'whilst suitable pieces othe lalloys '-"m per, isthen first conducted eithercirculating -rouscmosds is-.nndegak "of metal. Inl-order tof-johviate tha-presence ofan unreducedcop rrchlodedlie electrlyte 1s advantageo y passed"'into a-urther opposite'to each other-preferably, wit out the interposition of a diaphragm. As -the to reinedcanserve as the anode.- The -rening ca'n be i lthe usual current strength-. e., 100 .amperes the usualvolt carried" out7 for example, with r squaremetre-fandone of agesi. e., about 0.3 volt in the casey ofv a.

trodes. lhe tem rature is advantageously kept at 45?- 509 The refining is carried 'out 'as follows z-The electrolyte, containing copper as orio acid, for example, `10 to grams per liter, and a little common salt, `for example, 150 ms per liter, flows in 'theoxidation is blown and per, advantageously the copperthat Iis'to be refined,'in the form-'fof granule`s,wstrips of late, or 1n somefother desired' form, so that 1: vessel charged withcopper in the above mentione'd state A'-( granules,

etc.) before it flows However, an electrothe process, after removing` and zinc chloride, is freed from these by one or zinc-are separated cathodi- 1n accordance withtheir separation podiff...

refining of crude copper ,or copper allo `The following is an example of a mode of carrying out the invention. Letit be asof copper, 20% or` which anodes and cathode are l-ductionvessel clprous chloride besides alittle continuously; or in discontinuous manner into vessel into which air or ehlorme which'. 1n addition contains cop- 1. The process of lcopper or copper alloys which comprises' Vusing an electrolyte Acontaining cuprous chloof the usual chemical processes:

' The accompanying drawing is a diagrammatic vertical section of an apparatus em-- bodying the present vinvention and suitable is filled with thel solution of the electrol ,i-

into which dip the anodes amade of V car n or other ysuitable insolublematerial and the The combined'oxldation and vreduction vessel 1 the Areduction vessel B, the electrolyzeiv() .cathodes b made, forinstance, of sheet copper. VIt will be understoodthat during the material form the anode; while r the extraction of the copper or other'metals consuch-1 tained in the electrolyte, an insoluble anode must be used. The electrolyte solution may pass through an overflow c from the electrof lyzer C into the storage tank D, from which 1t is propelled upwardlythrough-a pipe ve by meansvof.v a pumping dev1ce\of any suitable character (not shown), which is connected with the pipe d. The pipe @discharges thevk -liquid into-the combined Yoxidation and re-4 A., The latter is filled-with copper .in the nature of-grains.- Into this.

vessel there is also introduced through' the -a stream of oxidizing gas,the unf pire g 'gjabsor ed or unused-part of which .escapes 'y through the outlet g. The treated, electrolyte solution passes' through a pipe [L the reduction' vessel B, likewise contaimng a' lling 'of copper in the nature ofgrainsj `From the reduction vessel B the electrolyte solution isv discharged into the electrolyzer C througbfan outlet controlled byte cock i.'

In'1operation,'thecock i is opened just suficientlyV to causeonly such-'an amount of as has been treated inthe manner described above. The arrows'indicate the path of elec-' trolyte solution and ofthe oxidizing Coppe/r-tin-'alloys can' alsobe refined ac-L cording to the `above process since tin is likewise. soluble in hydrochloric acid solution. y What'we claiinas our invention and desire to secure by-Letters Patent 5 v electrolytic'ally ridegpas'sing an Yelect-ric current throughfsaid electrolyte, said copperforvr alloys. used asftle anode, eonvertin`g the cupfonschlride after completion of l the electi'lyfss intol cupric chloride so1ution', actng thereon1 with metallic copper forredcingthe-cnpric chlo- 'intothe bath. 'of employing a singlet, siibstarnigially; 'completely' cu'PrOuS electrolyte solution to How back intojshebath meneer chloride'solution, and re-nsing the latter as electrolyte. 4

2. The process of electrolytically rening copper or copper alloys which consists in jusing an electrolyte containing cuprous chloride, passing an electric current through said electrolyte, said copper or alloys beingused v copper or copper alloys Which consists in l using an electrolyte containing cuprous chloride, passingban electric current through said l electrolyte, ringing `at least a part of the electrolyte out oftheelectrolizer, converting this part into cupric chloride solution by the vaction `ot a gaseous oxidizing agent and by means of metallic copper reducing the cupric chloride solution to cuprous chloride electrolyte, which is brought back to the electrolizer.

4. The process of electrolyticallyI reiining copper or copper alloys which consists in using an electrolyte containing cuprous chlojCil - this part into cupric chloride solution by theride, passing an electric current through said electrolyte, bringin at least a part of the electrolyte out of t e electrolizer, converting this part/into cupric chloride solution and bringing solid parts of the copper or copper alloy to bereiined into contact With the said cupric chloride solution for reducing it to' cuprous chloride electrolyte, until the original copper content of the solution is restored, and then conducting such part of the electrolyte back tothe electrolyzer.

5. The continuous process of electrolytically refining copper or copper alloys which consists in using an electrolyte containing cuprouschloride, passing an electric current through said electrolyte, converting'the cuprous chloride, aftercompletion of the electrolysis, into cupric chloride-solution and re'- vdcing the so produced solution to cuprous chloride electrolyte, and ait'er depositing all the copper from the electrolyte throwing out lyte, which is brought baclr te the electro lizer, and adding a colloid to the electrolyte.

ln testimony whereof We ax our signatures.

M liltlllq HSjENFELD. enn'rnnn ,nenn

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'by the action oi a gaseous oxidizing agent the dissolved other components cathodically in accordance with their separation potentials, and using the'chlorine. reduced atthe anode as oxidizing agent vor other spent cuprous chloride electrolyte. y

6.- The process of electrolytically refining copper or copper alloys which consists in using an electrolyte containing cuprous chlo- 5 ride, passin an electric current through said electrolyte, ringing at least a ,part of the electrolyte out of thel electrolizer, converting action ofqa gaseous oxidizing agent, adding a small quantity o hydrochloric acid and by means of metallic copper reducing the cupric l y chloride solution to -cuprous chloride electroiet lll@

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